Virtual Labs

DSB-SC, SSB-SC Modulator & Detector

In a DSB-SC modulation scheme, if the message signal contains frequency components up to 5 kHz, what is the minimum sampling frequency required to avoid aliasing according to the Nyquist theorem?

a: 5 kHz Explanation

Explanation

b: 10 kHz Explanation

Explanation

c: 15 kHz Explanation

Explanation

d: 20 kHz Explanation

Explanation

How does the phase shift of the local oscillator affect the demodulation of an SSB-SC signal?

a: The phase shift must match exactly the phase shift of the original modulating signal for optimal demodulation. Explanation

Explanation

b: The phase shift of the local oscillator does not affect the demodulation of an SSB-SC signal. Explanation

Explanation

c: The phase shift of the local oscillator enhances the signal-to-noise ratio of the demodulated output. Explanation

Explanation

d: An incorrect phase shift can result in significant distortion or loss of the message signal. Explanation

Explanation

What is the impact of a non-ideal filter on the recovered message signal in an SSB-SC system?

a: Non-ideal filtering reduces the overall signal power but preserves the message signal shape. Explanation

Explanation

b: Non-ideal filtering enhances the signal-to-noise ratio by removing unwanted frequencies. Explanation

Explanation

c: Non-ideal filtering can introduce distortions such as frequency distortions or amplitude variations. Explanation

Explanation

d: Non-ideal filtering does not affect the message signal if the filter's cutoff is set properly. Explanation

Explanation

In a DSB-SC system, what is the effect of phase mismatch between the transmitted and received carrier signals during demodulation?

a: Phase mismatch only affects the frequency of the output signal without altering its amplitude. Explanation

Explanation

b: Phase mismatch results in a reduction of the output signal amplitude and introduces significant distortion. Explanation

Explanation

c: Phase mismatch does not affect the demodulation process if the amplitude of the received signal is sufficient. Explanation

Explanation

d: Phase mismatch results in an increase in the overall signal power. Explanation

Explanation

What is the theoretical bandwidth requirement of an SSB-SC signal if the message signal bandwidth is 4 kHz?

a: 8 kHz Explanation

Explanation

b: 1 kHz Explanation

Explanation

c: 2 kHz Explanation

Explanation

d: 4 kHz Explanation

Explanation

How does the use of a balanced modulator impact the performance of a DSB-SC system?

a: A balanced modulator increases the power of the carrier signal in the output. Explanation

Explanation

b: A balanced modulator helps suppress the carrier and reduces unwanted spurious signals. Explanation

Explanation

c: A balanced modulator simplifies the receiver design by eliminating the need for coherent detection. Explanation

Explanation

d: A balanced modulator has no significant impact on the performance of the DSB-SC system. Explanation

Explanation

In an SSB-SC system, what are the primary challenges faced in achieving perfect carrier suppression?

a: Challenges are mainly related to the bandwidth of the message signal. Explanation

Explanation

b: Challenges involve the use of non-linear amplifiers in the transmission chain. Explanation

Explanation

c: Challenges are associated with the power of the transmitted signal. Explanation

Explanation

d: Challenges include maintaining precise oscillator frequency and phase synchronization, and handling non-ideal components. Explanation

Explanation

In DSB-SC modulation, what role does the Hilbert transform play in the signal processing chain?

a: The Hilbert transform is used to create the analytic signal, which is crucial for generating the modulated signal. Explanation

Explanation

b: The Hilbert transform adjusts the amplitude of the signal to fit the desired modulation index. Explanation

Explanation

c: The Hilbert transform is used to filter out the carrier frequency from the modulated signal. Explanation

Explanation

d: The Hilbert transform is used to demodulate the DSB-SC signal directly. Explanation

Explanation

For an SSB-SC signal, how can the presence of noise impact the phase detection process during demodulation?

a: Noise improves phase detection by spreading the signal's frequency components. Explanation

Explanation

b: Noise will only affect the amplitude of the received signal, not the phase detection. Explanation

Explanation

c: Noise can cause phase jitter, leading to incorrect phase detection and loss of signal fidelity. Explanation

Explanation

d: Noise does not affect the phase detection if the signal-to-noise ratio is high. Explanation

Explanation

What is the main reason for using a synchronous detector in the reception of DSB-SC signals?

a: A synchronous detector removes the need for a local oscillator in the demodulation process. Explanation

Explanation

b: A synchronous detector ensures that the carrier is properly aligned with the received signal, allowing accurate recovery of the message signal. Explanation

Explanation

c: A synchronous detector filters out any out-of-band noise from the received signal. Explanation

Explanation

d: A synchronous detector is used to amplify the received signal before further processing. Explanation

Explanation

In SSB-SC modulation, what is the primary reason for implementing a phase-locked loop (PLL) in the demodulation process?

a: A PLL enhances the amplitude of the received SSB-SC signal for better visibility. Explanation

Explanation

b: A PLL is used to lock onto the carrier frequency and phase, ensuring accurate demodulation of the SSB-SC signal. Explanation

Explanation

c: A PLL eliminates the need for a coherent detector in the demodulation process. Explanation

Explanation

d: A PLL reduces the bandwidth of the demodulated signal to fit within system constraints. Explanation

Explanation